Hi. lammps users
I’m trying to simulate the behaviors of graphene sheets when one sheet of graphene is opening.
So, i want calculate the surface energy.
But, in this process, i hava a problem.
The total potential energy and summation of per-atom potential energy are not same in my result.
How can it be?? I’m very confused.
This is my code.
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log grap1.log
# ---------- Initialize Simulation ---------------------
clear
units metal
dimension 3
boundary p p p
newton on
# ---------- Atoms definition ---------------------
read_restart graphene-5L.restart
# ---------- Define Interatomic Potential ---------------------
pair_style airebo 3.0
pair_coeff * * CH.airebo C C
neighbor 0.2 bin
neigh_modify delay 0 every 1 check yes
#--------------Setting-------------------------------
compute eng all pe/atom
compute eatoms all reduce sum c_eng
thermo 10
thermo_style custom step lx ly lz press pxx pyy pzz pe temp
#-------------Dynamic------------------------
# variables
reset_timestep 0
#variable natoms equal count(out)
variable Epot equal pe
#variable Epot0 equal {Epot}<br><br><br><br>variable NF equal fcm(out,z)<br><br><br><br>variable zo equal xcm(out,z)<br><br><br><br>variable zb equal xcm(bottom,z)<br><br><br><br>variable nf0 equal {NF}
variable zo0 equal {zo}<br><br><br><br>variable teng equal "c_eatoms"<br><br><br><br><br><br><br><br><br><br><br><br><br><br>fix 2 all nvt temp 300 300 0.01<br><br><br><br>fix 3 bottom momentum 1 linear 1 1 1 angular<br><br><br><br>fix_modify 2 energy yes # extended Hamiltonian for NVT<br><br><br><br>fix extra out print 10 "{NF}" file nf.txt
fix disp out print 10 “{zo}" file dis.txt<br><br><br><br>#fix disp1 bottom print 10 "Displacement = {zb}” file dis1.txt
fix disp2 all print 10 “${Epot}” file pe.txt
velocity out set 0.0 0.0 20.0 sum no units box
dump 1 all atom 10 dump.gra
thermo 10
thermo_style custom step temp pe lx ly lz press c_eatoms
run 400
quit
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And, the result shows different value between total pot and summation of per-atom energy.
Step Temp PotEng Lx Ly Lz Press eatoms
0 378.36359 -15392.957 31.461894 33.534282 100 1214.9496 -15392.957
10 341.0589 -15382.87 31.461894 33.534282 100 718.54157 -15392.349
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I’m waiting for your helps.
Thanks.
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